May 23, 2012
Options to Cut Inspection Time
We are forced to correct many solder defects on the PCB bottom side (SMD glue
The inspection and search for defects is taking too long.
Our soldering waves are not new, we have tried several
times to prevent these defects, but with old equipment we are
Would you suggest we investigate a 3D AOI system to save inspection time? Any other suggestions?
inspection is amazingly fast and accurate. It enables you to get the data you
Process Solutions Consulting Inc.
Lee Levine has been a Process Engineer and Metallurgist in the semiconductor industry for 30 years. He now operates his own company Process Solutions Consulting Inc where he consults on process issues and provides SEM/EDS and metallography services.
key issue is not to decrease inspection time, but to reduce your defects that
you are experiencing in your wave solder process. Without knowing the
types of defects that you must repair, I would suggest that you investigate the
use of nitrogen inerting for your wave solder process. In my past and
present experience the reduction of many types of defects, such bridging,
icicles, and insufficient solder can be reduced by using an inert
atmosphere. Some added benefits are dross reduction, that may be a cause
for your defects and the reduction of flux required per board. Reduction
in time to repair the defects, increased productivity and material costs =
overall cost savings. We offer a retrofit inerting kit to introduce
nitrogen to the solder pot and wave area.
Global Segment Manager
Air Products & Chemicals, Inc.
Mr. Arslanian has been involved in electronics packaging processing and equipment since 1981 including flipchip, TAB, wirebonding and die attach. Current responsiblities include R&D, applications, marketing and customer interaction.
Without much more knowledge of your situation, my gut reaction
would be to say "no." It's almost always better to invest in preventing defects
than in inspection and repair. That said, it may be that you have designs that
you are not in control of (customer design) and the design may be a big
contributor to the defects you are seeing.
The first step to solving this is to figure out the root causes - why does each specific defect type happen? Is it mainly because the design is
difficult or deficient, or mainly because the soldering equipment is incapable?
If the former, and you have no control over the design, then inspection may be
the only avenue. If the latter, then you can consider upgrades to the equipment
to eliminate the defects.
Only after you have exhausted all resources to understand the
root causes of the defects and eliminate as many of them as possible should you
consider investments in automated inspection. Remember that the initial cost of
AOI is not the only cost. You will also be faced with the cost of programming,
which may be substantial. You will also be dealing with some level of "false
positives" which will be an ongoing cost that must be minimized by optimization
The big up-side to
AOI is that it is very efficient, unlike manual inspection which will
inevitably miss as many as 30% of defects. AOI also allows you to more easily
log defects into an SPC system, which can lead to much faster, easier
identification of root causes.
Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.